A total of four vehicles were involved, including a stalled car, a car that hit the stalled car, a vehicle that the big rig, and the big rig, according to the California Highway Patrol. The driver of the stalled car was nowhere to be found. A silver car was seen mangled along the highway.

It's not clear exactly how the rig flipped, according to CHP Officer Whitney Howard, but there is the "possibility that someone did flee the scene." Witnesses told the CHP they thought they saw someone that might be related to the accident leaving the area, Howard said. She added there were a lot of "conflicting" stories.